Script windows take full advantage of the language-sensitivity features of Scintilla, such as color-coded syntax, popup help, auto-completion, function parameter prompting, parentheses balancing, multi-level undo/redo, smart tabbing, block comment in/out, etc.
The popup above shows all available syntax containing "si", since that is what was typed so far.
You can also at any time press F2 in a script window to see all available syntax options for where the cursor is.
The cursor was one tab in, under "ExitRule", so the List shows all available strategy elements.
See the Script Menu documentation for more about what can be done in a Script Window.